Variable load brake



March '12, 1946. G.. T. MccLuRE VARIABLE Lomi BRAKE Filed Feb. 2'?, 1945 lNVENTO GLENN 1i Mc CLURE Patented Mar. l2, 1946 VARIABLE LOAD BRAKE Glenn T.`McClure,. McKeesport, Pa., assigner toI The Westinghouse Air Brake Company Wilmerdin'g; Pa.,.a corporationof Pennsylvania` Application February 27, 1943', Serial Nol'437-73385l 1l) Claims. (Cl. 34031-22) This invention relates to variable load uid pressure brakes, in which the braking power is automatically varied according to variations in the weight of the lading onthe vehicle.

The principal object of the invention is to provide an improved variable load brake apparatus of the above mentioned type.

Another object of the invention is to providea novel variable load brake apparatus which is so constructed and arrangedfthat, when thebrake pipe pressure is being increased in charging, it will be automatically conditioned or changed over from empty braking to any degree of load brak-y ing, calledfor by the weight ofthe lcadcarried by the body of the vehicle, 1and which, when the brake pipe pressure exceeds a predetermined limit, will be maintained in itsconditioned state-so long as the brake pipe pressure is not reduced: belowy said predetermined limit.

Still another object of the invention is to provide a novel' vehicle variable load brake mechanism which may be used in conjunction with a standardr air brake equipment for the purpose of controlling the (brake cylinder pressure in-accordance with the brake pipe reductionand-with various weights of loads carried byy the vehicle.4

Other objects and advantages will appear in the following detailed description of. the invention.

In' the' accompanying drawing Fig. 1 is a diagrammatic view, partly in section,

of a' variable load brake apparatusconstructedl in accordance with the invention.

Fig. 2 is a sectional'view, on an enlarged'scale, of that portion of the variable load'valve mechanism associated with a truck of the vehicle and shown in outline in Fig. 1, the view being` taken on the line 2 2 of Fig. 1.

DESCRIPTION As shown in Fig; 1, the variable load fluid pr'es'- sure brake equipment may'comp'rise'a brake pipe l, a brake controlling valve device 2, an auxiliary reservoir 3, an emergency reservoir 4, a brake cylinder device 5, a change-over control valve device 6, a variable load valve mechanism 1, a

volume reservoir 8', and two non-return check' February 18, 1936, and in view of this itis deemed unnecessary to show: and describe the device in detail; mechanism operates upon a service reduction in f brake pipe'press'uretosupplyfluid'under'pressure from the' auxiliary reservoir vtc the braker cylinder 5 t'o effect'a service application of the brake, uponlanemergency reduction in brake pipefpres'- sure, to supply uid under lpressure from bot-h the auxiliaryl and emergency reservoirs 3 and 4,

respectivelyg-t'o th'ebra'ke cylinder 5- to effect anemergency application of the brakes and'upon an increasein brake.pipepressureltoeffect a releasel of' brakes4 and the charging offthebrake equipment.

The: change-over controlvaive device B, whichl may besmounted'onthe car body,may comprise a two-piece; casing havingv clamped therebetween a` iieXible diaphragm I2. At` one si'de ofthis diaphragm thereis a chamber I'3 which is constantly connectedthrough a passage I4 with-the' atmosphere. At` the opposite side of thev diaphragm there is aI valve' chamber i5. which is constantlyconnected-through a'passageland pipeA i6 and pipe Contained ini valve chamberv l5 is a slideivalvef H` which is adaptedto befoperatedr by a stem I 8f operatively connected to 'thediaph'ragm' I 2 in. any Contained in chamber I3 is a: spring lllfvvhich` at all time, tendsto urgethe diaphragm l2, stem` IS'and-slidevalve IT toward 'the position in which they arev shown in th'e suitable manner.

drawing.

Thevariableloadvalve'mechanism l comprises a casing structure which is rigidly secured in any suitable mannerl to a sprung part of the vehicle,

. such, for instance,A as' the truck bolster 2t]` of a truck` of the vehicle. As illustrated, the'l casing structure comprises a` brakeL cylinder pressure control Valve portion 2| and ar Weighing portion 2?r operativein accordance with the load carried-by the vehicle, to control thefbrake cylinder pressure control valve portion 2|.

As best shown in Fig- 2, the casing portion tionvof its seatedzposition by-'thepressure of a coil spring-30; and isadapted to control communication between the pressurechamberl 24 anda-duidpressure passage v3| formed in the casing, The

brake. c y1inderpipe- Zi, which leadsv trom the" It will, o'f course, beunderstoodthat this" brake controlling valve device 2 to the brake cylinder 5, is connected through a pipe 33, the check valve device 9 and pipe 32 with the passage 3|. The check valve device 9 is interposed in the pipe 32 and is operative to prevent back flow of uid under pressure from the pipe 32 and thereby from the pressure chamber 24 to the pipe 33 and brake cylinder 5. The check valve of the device 9 is biased in the direction of its closed position by a spring so as to insure that a predetermined pressure will be established in the brake cylinder before it will operate to permit flow from the brake cylinder to the pressure chamber 24.

Mounted in a suitable bore formed in the casing and in parallel relation with the valve 29 is a piston 35, which is subject on one side to the pressure of fluid in the chamber 24 and on thev other side to the opposing pressure of a coil spring 36 that is disposed in a chamber 38,which communicates by way of a passage 39 with the atmosphere.

The valve 29 and the piston 35 are both adapted to be controlled by operation of a lever 42 which is pivotally mounted intermediate its ends on a pin 43 carried by a plunger 44 which is slidably mounted at one end in a suitable guide bore 45 formed in the casing. One end of the lever 42 is provided with a roller 46 which is engageable with the outer end of a projection 41 formed on the outer face of piston 35, while the other end of the lever 42 is pivotally connected to a rod 48 which is operatively aligned with the supply valve 29. The other end of the plunger 44 engages a cam U rigidly secured to an operating shaft 5|. The shaft 5I is rotatable in bearings formed in the casing, and has secured to one end, which extends to the exterior of the casing, an operating lever 52 operative to rotate the shaft as hereinafter described.

The casing of the weighing portion has formed therein a bore 55 in which there is mounted a piston 56 having a stem 51. At one side of piston 56 there is a chamber 58 which is connected to a passage and pipe 59 leading to the change-over control valve device 6. At the opposite side of the piston 56 is a chamber 60. The piston stem 51 passes through chamber 60 and extends through laterally extending wall 60' of the casing to the interior of chamber 60 and at its end is adapted to engage one side of the operating lever 52 hereinbefore mentioned. Also contained in chamber 66 and surrounding the stem 51 is a spring 6I which is interposed between and operatively engages the piston 56 and the wall 60' of chamber 60.

Slidably mounted in the weighing portion of the casing is a rod 62 which is rigidly secured in any suitable manner to that portion of the stem 51 which extends below the wall 60'. The rod 62 is so constructed and arranged as to permit the lower end thereof to engage a stop member 63 carried by an unsprung part of the truck, such, for instance, as a truck side frame 65, for a purpose hereinafter described.

Mounted in a suitable bore 66 formed in the casing of the weighing vportion and in vertical aligned relationship with the piston 56 is a piston 61, -which latter piston is smaller in diameter than the piston 56. At one side of piston 61 there is a chamber 68 which is also connected to the passage 59 leading to the change-over control valve device 6. At the opposite side of the piston 61 there is a chamber 10.

The piston 61 is provided with a stem 1I which passes through chamber 16 and extends through a wall 10' of the casing to the exterior of chamber 16 and at its end is adapted to engage the opposite side of the operating lever 52. Contained in chamber 16 and surrounding the piston stem 1I is a spring 12 which is interposed between and operatively engages the piston 69 and the wall 16'. It will be understood by those skilled in the art that when the vehicle is empty, the truck bolster 26 will be in its normal or uppermost position, as shown, and that as the load carried by the truck increases, the usual truck springs 8U will be compressed so that the truck bolster will move downwardly relative to the truck side frame and that this relative movement will always be proportional to the weight imposed on the truck bolster 20. As this movement occurs on trucks equipped with the present embodiment of the invention, the clearance or distance between the lower end of rod 62, carried by the piston stem 51, and the stop 63 is reduced.

OPERATION Initial charging of the equipment Assuming the vehicle, embodying the invention to be empty and separated from a train, the brakes ron the vehicle to be released, the brake pipe I of the vehicle to be deplete of fluid under pressure, and the operating lever 52, of the brake cylinder pressure control portion 2l of the variable load valve mechanism 1, to be temporarily disposed in the position in which it is shown, i. e. full load braking position. Under these conditions, the brake controlling valve device 2 will be in release position and the several other parts of the equipment will all be in the position illustrated in the drawing.

With the operating lever 52 in full load braking position as shown in Fig. l, the operating cam 50 is also in full load braking position as shown in Fig. 2. With the cam 50 in this position, the outer end of the plunger 44 may be either in Contact with the cam surface, as shown or in close proximity to said surface. It will be noted that the cam in its full load braking position may not exert any inward pressure on the plunger 44 so thatthe pressure of the spring 3U maintains the valve 29 seated.

Now if the empty vehicle is placed in a train,

the brake pipe I will of course be connected at each end of the vehicle to the corresponding brake pipe at the adjacent end of each adjacent vehicle lin the train and as a result will be charged with uid under pressure in the usual manner. Fluid under pressure thus supplied to the brake pipe I flows through a branch pipe 15 to the several chambers of the brake controlling valve device 2 which are to be charged, and from the brake controlling valve device, the iiuid flows in the usual manner, to the auxiliary reservoir 3 and the emergency reservoir 4 by way of pipes 16 and 11, respectively, in the usual manner.

Fluid under pressure iiows from the branch pipe 15 to the slide valve chamber I5 in the changeover control valve device 6 by way of connected pipe and passage I6, the spring I9 maintaining I the diaphragm I2 and attached slide va1ve-I1 in the position shown until, as presently described, a predetermined pressure has been built up in the valve chamber l5.

Fluid under pressure supplied to chamber I5 of the change-over control valve device 6 ows to chambers 58 and 68 in the Weighing portion 22 of the variable load valve mechanism 1 by way of pipe and passagev 59. Fluid under pressure thus supplied to chamber 58 causes the piston 56, stem 51 and attached'rod 62 to. move downwardly from the position viewed in Fig. 1 of. the drawing. Since, as shown, the outer' end of the piston stem 51 engages the upper side to the operatinglever 52, any downward movement of the stem 51 will effect clockwise rotation of the lever 52. Fluid under pressure supplied to chamber 68 causes the piston 61 and attached stem 1I to move upwardly in opposition to spring 12 until the outer or upper end of stem 1I engages the lower surface of the operating lever 52.

Since the area of piston 56 is larger than that of piston 61, the piston 56 and attached stem 51 will be caused to move downwardly under the influence of an increase in pressure in chamber 58 against the opposing pressure of spring 6|, and the pressure of fluid in chamber 68 acting through the medium of piston 51, stem 1I and operating lever 52. As the piston 56 and attached stem 51 continue to move in this direction the operating rod 52 and the operatively connected shaft 5I are caused to rotate in a clockwise direction from the position in which they are shown in Fig. 1 of the drawing. The piston 56, stem 51 and attached rod 62 continue to move downwardly, causing continued rotation of the operating lever 52 and shaft I until the piston 56 and attached stem 5'! are brought to a stop by the end of the rod 62 coming into engagement with the stop 63.

When the piston 56 and attached stem 51 are thus brought to a stop by the lower end of the rod 62 engaging the stop S3, the piston 61 and attached stem 1I will act to maintain the operating lever 52 and thereby the brake cylinder pressure control valve portion 2| of the variable load valve mechanism in its empty position.

Clockwise rotation of the shaft 5| due to rotation of the lever 52 causes the cam 5D carried by the shaft to rotate in the same direction. As the cam is thus rotated, the cam surface engages and forces the plunger 44 and pivot pin 43 inwardly, i. e., in a direction toward the left hand as viewed in Fig. 2 of the drawing. Since the spring 36 acting on one side of piston 35, offers greater resistance to inward movement of the lever 42 than does the spring 3D acting on the Valve 29, the piston 35 is maintained stationary, so that a pin 82 for the roller 46 located at one side of the pin 43, becomes the fulcrum for lever 42.` Thus, as the plunger 44 and pin 43 are moved inwardly by action of the cam 5l), the lever 42 is caused to rock about the pin 82 and through the medium of the rod 48, attached to the opposite end of the lever 42, causes the supply Valve 29 to be unseated against the opposing pressure of the spring 39.

Now when the pressure of fluid in valve chamber I5 of the change-over control valve device 6 has been increased to around 35 pounds, the diaphragm I2 will be caused to deflect in a direction toward the right hand against the opposing pressure of spring I9. The diaphragm, as it thus deilects, acts through the medium of the stem I8 to shift the slide valve I1 in the same direction. When the deflection of the diaphragm I2 is brought to a stop by means of an extension v83, carried by the stem I1, engaging an interior surface of the casing, the slide valve I 8 will have been moved into a position in which a cavity 84 therein connects the pipe 53 to an atmospheric passage 85. With this communication established fluid under pressure in chambers 58 and 68 of the weighing portion 22 of the variable load valve mechanism 1 is quickly vented to the atmosphere, by way of" passage andpipe4 59, cavity-84' in the `slide valve.

I8 of the change-over controlvalve devlce=6 and atmospheric passage Upon a reduction, in pressure inl chambers 58 and:68,springs6l and 1Ilactingon` the pistons-'56 and 61, respectively, willv cause-each pist-onand attached stem to moveto the position inzwhichfthey are shown in the drawing. It will be understood that friction between the shaft 5I and its bearing surfaces will be sucient to maintain the operating lever 52 in its adjusted position when the respective piston stems 51 and.1I are moved outof engagement therewith. It will also beunderstood that since, the piston stems. 51 and 1I are moved out of engagement with the operating leverv 52 when the adjustment ismaderel`ative motion-between the truck bolster 20 andthe side. frame 65 will not affect the position of the lever. andlthereby the adjustment of the brakecylinder pressure controlvalve portion ZI of the variable load valve mechanism 1 when the vehicle is in motion-andthat the-mechanism will remain initsempty vehicle position until the uid under pressure in chamber I5 of the change-over control valve de vice is again reduced lbelow the value of springv I9;

APPLICATION oF THE BRAKEs'oN ANEEMPTXS VEHICLE When it is desired to effect an application of the brakes, the brake pipe pressure is reducedzin the usual manner, causing the brak'econtrolling valve device 2 to function to supply uid under pressure from the `auxiliary reservoir 3 to the'br'ake cylinder 5 in order to advance the usual brake shoes (not shown) into frictional engagement with the Vehicle wheels. The flow of fluid under pressure from the auxiliary reservoir to thelorake cylinder is by way of a pipe 16, through the brake controlling valve device 2 and connected brake cylinder pipe 34.

When the pressure of fluid thus supplied tothe brake cylinder 5 has increased to a predetermined degree, sufficient to insure that the brake. shoes have been moved into-frictional engagement with the vehicle Wheels, such, for instancey 5 tor 7 pounds, the spring Weighted check'valvedevic'e 9' will unseat and permit flow of uid from the brake cylinder pipe 34'to the' chamber28'inthev brake cylinder pressure-control portion 2I ofthe variable load valve mechanism 1. The' flow of fluid from the brake cylinder pipe by wayof pipe 33, pipe 32 through the` open check'valvede'- vice 9 and passage 3 I.

Fluid under pressure thus supplied to chamber 28 flows past unseated valve 29 to chamber 24.

from whence it flows by way of passage andpipe 25 to the volume reservoir 8, which in effect', acts as a dummy brake cylinder.

It should here be mentioned that so longas the brake cylinder pressure control portion 2l of the Variable load valve mechanism 1 is conditioned for empty vehicle braking` the valve" 9` thereof will be maintained unseated.`

Now as the pressure of fluid supplied to the brake cylinder and connected pipe 32is increased; the pressure of fluid in chamber24 of the brake cylinder pressure control portion 2'I of the variable load valve mechanism 1 and connecte'd'vol'- urne reservoir 8 is increased to effect an application of the brakes to the degree desired. When a full service application of the brakes iseected the pressures of the auxiliary reservoir 3and the brake cylinder 5 will equalize and the pressure of the reservoir 8 will be lower than this pressure by an amount equal tothe value of the spring. which weights the check valve of the devic'eLS. Since fluid under pressurel is supplied through pipe 34 to both the brake cylinder and the reservoir 8 the equalized pressures of the auxiliary reservoir and brake cylinder will be considerably lower than if the auxiliary reservoir pressure equalized into the brake cylinder alone, thus the desired maximum brake cylinder pressure for an empty vehicle is attained.

RELEASE E THE BRAKES WITH THE EQUIPMENT CoNDITIoNED FOR EMPTY CAR OPERATION When it is desired to effect the release of the brakes the brake pipe pressure is increased in the usual manner, causing the brake controlling valve device 2 to function to establish communication from the brake cylinder pipe 34 to a pipe 8B which leads to the atmosphere. Fluid under pressure now flows from the brake cylinder 5 to the atmosphere by way of pipe 34 through the brake controlling valve device 2 and pipe 88. Fluid under pressure in the volume reservoir 8 also flows to the atmosphere by way of pipe 33, past the check valve I0 interposed in said p-ipe to connected pipe 34 and then through the circuit just traced. Upon the release of fluid under pressure from the brake cylinder 5, the brake cylinder is caused to operate in the usual manner to effect a release of the vehicle brakes.

AUTOMATIC CHANGE-OVER OPERATION or THE EQUIPMENT oN A PARTIALLY LOADED VEHICLE .Assuming now that the brakes on the vehicle are released and that the vehicle is separated from a train and that while the brake pipe is deplete of iiuid under pressure, lading is placed on the body of the vehicle. Under the influence of such additional weight the vehicle body and consequently the truck bolster 20 will move downwardly relative to the vehicle side frame 65, the bolster supporting springs 88 yielding to the additional weight. Since, as hereinbefore mentioned, the variable load valve mechanism 1 is carried by the bolster and the stop 63 is carried by the truck side frame 65, it will be obvious that the clearance or distance between the lower end of the rod 62, carried by the mechanism 1, and the stop 63 is dependent upon the distance the truck bolster moves vertically relative to the truck side frame.

Now when the vehicle is connected in a train the brake pipe starts to charge with fluid under pressure in the same manner as hereinbefore described in connection with the charging of an empty vehicle. As before described uid under pressure supplied to the brake pipe flows to chamber I5 in the change-over valve device 6, from whence it ilows by way of pipe,59 to chambers 58 and 68 in the weighing portion 22 of the variable load valve mechanism 1. Fluid under pressure thus supplied to chamber 53 causes the piston 5E, stem 51 and attached rod G2 to move downwardly in opposition to spring Gl until brought to a stop by the end or the rod G2 coming into engagement with the stop 63. Since it has been assumed that the vehicle was empty, prior to the additional weight being imposed thereon, the operating lever 52 will now be in the position to which it was previously moved with relation to valve casing, it being understood that, due to the downward movement of the truck bolster, it will be in a lower plane. The operating lever in this position will be in operative engagement with the outer end of the stem 1|. Fluid under pressure supplied to chamber 68 causes the piston 61 and attached stem 1| to move upwardly in opposition to the pressure of spring 12.

With the outer end of stem 1| engaging the operating lever 52 it is obvious that such upward movement of the piston 61 and attached stem 1| will cause the operating lever 52 and operatively connected shaft 5| to rock in a counter-clockwise direction until brought to a stop by the operating lever 5| coming into engagement with the outer end of the piston stem 51 which is positioned according to the weight of the lading carried by the vehicle. Since the area of piston 51 is larger than the area of piston 61 and since both pistons are subject to the same fluid pressure it will be apparent that the operating lever 52 will be maintained in this position.

When the brake pipe pressure is increased to the degree required to eiect operation of the change-over control valve device, this device will operate as before described to vent fluid under pressure from the chambers 5B and 68 of the weighing portion 22, thus permitting the springs 6I and 12 to return the pistons 56 and 61, respectively, to the positions in which they are shown in the drawing, the operating lever 52 remaining in the adjusted position.

It should here be noted that as the operating lever 52 and the operatively connected shaft 5| are rotated in a counter-clockwise direction, from empty position through the partially loaded zone in a direction toward full load position, the cam surface of the cam 50 tends to gradually recede from the end of the plunger 44. As this occurs the spring 3G acts to move the piston 35 outwardly, i. e., in a direction toward the right hand, the piston, as itis being moved, rocking the lever 42 in a counterclockwise direction about a pin 89 which is maintained stationary by the resistance offered by the spring 30 through the medium of the valve 29 and the rod 48 and as a result the plunger 44 and lever 42 move in a direction toward the right hand, the plunger remaining in contact with the cam 50 but following the receding surface thereof. From this it will be understood that the brake cylinder pressure control portion is constructed and arranged to operate automatically to control the communication between the brake cylinder and the reservoir 8 in such a manner as to provide for a higher brake cylinder pressure as the load on the Vehicle is increased.

Now with the operating lever 52 and thereby the brake cylinder pressure control portion 2| of the variable load valve mechanism positioned in a braking zone, between full load and empty, in accordance with the load added to the vehicle, the brake equipment is conditioned for braking.

APPLICATION oF THE BRAKES 0N A PARTIALLY LOADED VEHICLE When an application of the brakes is initiated on a partially loaded vehicle by effecting a reduction in brake pipe pressure, the operation of the brake controlling valve device 2 will be identical with the operation already described for an empty vehicle. From this it will be understood that fluid under pressure will be supplied to the brake cylinder until increased to a degree suiiicient to unseat the spring weighted check valve 9, whereupon fluid under pressure supplied to the brake cylinder pipe 34 and thereby the brake cylinder will also iiow to chamber 24 in the brake cylinder pressure control portion 2| and connected volume reservoir 8.

Now when the pressure of fluid in pressure chamber 24 acting on one side of the piston 35 is slightly greater than the opposing pressure of the spring 36 acting on the other side of the piston, the piston will move inwardly which, in

agee-m4a1 `the r present=.embodimentrof-the inventions is iin i a direction ltoward *thee-left rhan'd.

As therpistonV is thus i being fmoved, :the :action of the spring f 30 causes 'the tsupply' :Valve 29 to move :toward 'its-:seat vThrough" the medium of the rod T48, the action-:ofsthe'valve 29fcausesthe lever 42 to rock about the pivotipinv 43,;n1 a; clockwise "'directcn. New A-when the fsupplyrvalve 129 seats, ffur'ther :flowf of f'fluid under. pressure :from the brake cylinder to the'volumeg-reservoirv'is closed oi andtheinward movement kof the piston y3 5i is stopped by the action ofathe springf36. F Since the piston-'135 is" broughtftofavstopl atx substantially the @same Atime fas 1 the supplyvalve 29:.fseats, the spring "30 Awill' act tomaintain thersupplylvalve seated. Thus 'the ibrake :cylinder pressure centrol Yportion i12 l is "yA-automatically 4operatedf in .accordance with the loadE carriedivbythe :vehicle-to control the :period of timeV the :communication between the brake: cylinder. and the vreservoir-i remainseopen.

l-With' thefiflow'off uid': under pressureffromsthe brake cylinder-5 "to .the wolume-reservoir cutoff, any further iiow' of'iuid-` under pressure'fromthe auxiliary reservoir 3 to'the:brake:fcylinderiwill result in afdirect builds-up -in 'brake'.'cylinder pressure.

RELEASE or' THE BRAKES WITH THE 'EQUIPMENT CON- .DITIoNEnEoMi PARTIALLYTLQADED .VEHICLE `.When -a release yof tha-brakes: iis-.feiectedaon n' a partially loa-ded vehicle, the :operation of :the brake controlling valvefdevice 2i-'to freleaseuid under: pressureffromt:both:r ther-brake cylinder; device 55:' and'*the*volumeznto-zthe atmosphereiywill be identical :with the: operationealready:described for anemptyvehicle.

As' the pressure in: .the v.volume reservoir ySeand connected chamber'Zll in thel'bralge cylinder.r pressure control portaient 2 l-rerluceszV theirspring E ,acts to move :'the -pistonL35-in= afdirection toward* the left fhand I.and with .'-the :cam "held f stationary in the f position' touwhich: it has sbeeni adjusted aand 4the plunger C44 consequently -hel'd @against outward movemenunthezpiston causes :the lever 42ito rock zury a' counter-clockwise.` direction uabout :the Vpin"l|"3. vAsthelpressure of -uid fchamberzll continues to -re'duce `thelever e142 l#continues `to Tockfand;1throughitheimediunro the rod-A8,'acts to unseatithe @valve :529 :against zthe :opposition :of

`'the spring F30 :whentheapressuresin the .chamber 221| isire'dueed to substantiallyzzero. :Fromzthisfit "willi-be:understoodithat the ibrakercylinder pres- A'sure @control f portion vl2 I -iis automatioallyxconditional for the next succeedingsapplicationfOfizthe f brakes.

fAUTOMATICTCHANGEfDVER ORERATION oF trHE EQUIPMENT,oNaEULLYLLQAnEnYEHIcLE A'Assuming new 'thatA the-rbr'akesr onf `thetvehicle are released Aand-` the vehicleaseparated' from :a train and that whilethebrakefpipe isideplete of 'iuid Aunder' pressure, f' the'J vehicle f is :fullyl loaded. From-the previous description in connection `with a partially loaded` vehicle itewill EYbe'understood that, withvv the vehicle-fully loaded,-I thedistance v`or-clearamzebetween thelowerendfoff-ro'dwGZ- and "the-stop63- wi1lbe reduced to? itsrm-in-imumvalue. "1t wwill -`also v be lunderstood, *from :the previous "description, that Ywhen thei vehiclefis f connected in "af train; the brakeflipee'fstartsSito fchargewith duid 'luiderY pressure-end -'thati-suchi'uidi-under pressure' :"lowsto4`- the'fchambersl 8f=and=6 8i in; the weighing `'portion 22 `A`of theivar-iabie rloads-.valve -mechanism '-Fromi-.the#description in.r connecposition, the cam 50` tion with a vpartially'loaded =fvehiclez-it will tbe understood that the pistons 56 and 68 will v'be caused to "operate, Abyfsuch fluid, Lto :position the operating lever 52 `andthereby'thezshaftl:of the brake -cylindercontrol 4portion 2l in :its vfull load f position in which Vpositionfit is shownv in the drawing. 'It' will however beYunderstfnzid'zthatthe lower endv of the rod "S2-will:be-closer'tothe lug yE53 than shown. Y

PWhen the brake pipe lpress-ureisincreased to the degree required toxefect :operationofthe change-over control -val-ve device f6, ithis :device will operate as ,beforeqdescribedz toi'vent ;uid'.un der v pressure :from rthe chambers :58 and r68 and thus v permit the springs 5| f; and 12 :tomove Lthe pistons 5Band 61 withtheir:attachedstemsl and 1l, respectively, :to the "positionvshown, thus conditioning thee-Variable floadfmechani-sm v:forfull loadbraking.

As hereinbefore ymentioned,- wvith thebrake cylinder pressure control portion 2l :fullrload will not exert any inward pressure o the plunger-.4,4 so thatthe pressure of the spring t3i! maintains t thewalve `.-2-9 seated, thus "communication between ;the` brake :cylinder 5 and the volume vreservoirf'tlzis maintainedscut 01T when the vehicle :is` fully flea-ded.

APPLIcATIoN or THEBRAKES .,oN A' FULLY YLOADED `2VEHICLE Now when a full vservice vapplication of 'the 'brakes is effected on thefully loaded vehicle; the brake controlling valve `device' 2 will operatef-in theusual manner to -supplyuid under #pressure from the auxiliary reservoir 3 tothe brake-'cylinder '5 until sucn-'pressures-:are equalized.

In eiecting an emergencyfapplication ofthe brakes on a fully loaded vehicle ythe auxiliary reservoir emergency reservoir and brakecylinder pressures will equalize. y

'When a vsubsequent release of `the `Abrakes is effected'the brake controlling valve device`21wll 'function as' hereinbeforel describedto releasefluicl under pressure from the `brake cylinder'and' thus effect-a release'of the--brakes'in the usual manner.

jSUMMARY :When a brake i application is 'feiectecl :non 1an -empty vehiclejembodying the'invention; thevari- -ablei load` mechanism `will Vbe so vconditionedf as'zto permit uid under pressure :.fromthf'fauxiliary reservoir to flow to iboth the :brake cylinder t5 and 'the' volumefreservoir 8. When; a brake-sapy plication' is *effected on',aifu11y` loaded=vehicle,;,em bodyiug` thel invention;fthe'variablevload mecha- -nismfwill be so "conditioned-that-:auxiiiary reser- Voir I pressure will flow 'only to the'fbraker cylinder-'5; and when the vehicle is partially loadedtthe increase in pressure in `thederakei'cylinderswill be controlledaccording to'thefperiod'of'ztime .that the vcommunication Ybetween the brake icylinder and reservoir #8 remains topen irwhich rperiod :tof time `depends :upon the weight of the yladingf'ear- -riedbythevehicle. ille-variable load mechanism f operates so that the maxi-mum pressure::sde veloped infthe bra-ke cylinder-in aifull `alzzplication of thebrakesin emptyioperationwillbe substan- -tially less -gthanfthat zon. a -fullf-amnlication of the brakes: during full loadcperation,4 yandrin which a :proportional pressureawillrhefdevelepediinethe xbrake;cylinderwhen:themehieleis;partiallysloaded or when less than n full vservice fapplication 1S eiected. i

Having now described .fm-yfiinvention, what -T claim as new and desire to secure by Letters Patent is:

l. In combination, a brake cylinder device, a volume reservoir, a brake controlling valve device operative to supply fluid under pressure to said brake cylinder device and to said volume reservoir, means adjustable in accordance with the load carried b v the vehicle, a brake pipe normally charged with fluid under pressure, means responsive to the pressure of uid in said brake pipe only when such pressure is less than a chosen degree for effecting operation of said means, and valve means for controlling the flow of iiuid under pressure from said brake controlling valve device to said volume reservoir. said valve means being conditioned by said means for operation to limit the pressure of iluid in said volume reservoir inversely according to the degree of load carried by the vehicle to thereby vary the pressure oi' fluid in the brake cylinder directly according to the load.

2. In combination, a brake cylinder device. a volume reservoir, a brake controlling valve device operative to supply fluid under pressure to said brake cylinder device and to said volume reservoir, means adjustable in accordance with the load carried by the vehicle, fluid pressure responsive means including a movable abutment subject to the pressure of fluid in a chamber and a spring operative for controlling said means. automatic lapping valve means for controlling the flow of fluid under pressure from said brake controlling valve device to said volume reservoir. said valve means being conditioned by said means for operation to limit the pressure of fluid 1n said volume reservoir inversely according to the degree of load carried by the vehicle to thereby vary the pressure of fluid in the brake cylinder according to the load.

3. In combinationa brake cvllpder device. a volume reservoir. a brake controlling valve device. a communication through which fluid under pressure is supplied from said brake controlling valve device to said brake cvlinder and said volume reservoir, means adjustable in accordance with the load carried by the vehicle. and selflapping valve means interposed in said communication between sald brake cylinder and said volume reservoir conditioned by said means for operation to one position for maintaining said communication closed to prevent any increase in pressure in said volume reservoir and to another position for maintaining said communication open to permit a maximum increase in pressure in said volume reservoir and adjustable between said positions to vary the increase in pressure in said volume reservoir inversely according to the degree of load carried by the vehicle to thereby vary the pressure of fluid in the brake cylinder directly according to the load.

4. In combination, a brake cylinder, a volume reservoir, a brake controlling valve device operative to supply iluid under pressure to said brake cylinder and to said volume reservoir, valve means having a normal position for closing the communication through which fluid under pressure is supplied from the brake controlling valve device to the volume reservoir and operative to another position upon a predetermined increase in the pressure of fluid supplied thereto for opening the communication, and automatic lapping valve means interposed between said valveA means and said volume reservoir for controlling the flow of iluid under pressure from said brake controlling valve device to said volume reservoir with said valve means in said other position, said automatic lapping valve means being conditioned to limit the pressure of fluid in said volume reservoir inversely according to the degree of load carried by the vehicle to thereby vary the presj sure of fluid in the brake cylinder directly according to the load.

5. In combination, a brake cylinder, a volume reservoir, a brake controlling valve device operative to supply fluid under pressure to said brake cylinder and to said volume reservoir, a spring weighted check valve for normally closing the communication through which iluid under pressure is supplied from the brake controlling valve device to the volume reservoir and operative upon a predetermined increase in pressure of iluid under pressure supplied thereto to open the communication, valve means interposed between sald check valve and volume reservoir for controlling the flow of fluid under pressure from said brake controlling valve device to said volume reservoir with said check valve in its communication open position, said valve means being conditioned for operation to limit the pressure of fluid in said volume reservoir inversely according to the degree of load carried by the vehicle to thereby vary the pressure of fluid in the brake cylinder directly according to the load.

6. In combination, a brake cylinder device, a volume reservoir, a brake controlling valve device, a communication through which fluid under pressure is supplied from said brake controlling valve device to said brake cylinder and said volume reservoir, valve means interposed in the communication between said brake controlling valve device and said volume reservoir for normally closing the communication to the volume reservoir and operative to open said communication upon a predetermined increase in the pressure of fluid supplied thereto, means adjustable in accordance with .the load carried by the vehicle, and self-lapping valve means interposed in said communication between said volume reservoir and said valve means for controlling the flow of lluid under pressure from the brake controlling valve device to the volume reservoir with said valve means in its communication open pcsltion, said self-lapping valve means being conditionedl by said means for operation to limit the pressure of fluid in said volume reservoir inversely according to the degree 'of the load carried by the vehicle to thereby vary the pressure of iiuid in the brake cylinder directly according to the load.

1. In a variable load brake apparatus for a vehicle truck having a relatively stationary part and also having a part movable vertically relative to the stationary part as the load on the vehicle is increased, in combination, a brake cylinder, a volume reservoir, control means for supplying fluid under pressure to said brake cylinder and said volume reservoir, means adjustable in accordance with relative vertical movement between the movable and stationary parts of the vehicle, a fluid pressure operated mechanism carried by the movable part and comprising a strut movable into engagement with the stationary part for adjusting said means, and valve means for controlling the ilcw of fluid under pressure from said brake controlling valve device to said volume reservoir, said valve means being conditioned by said means for operation to limit the pressure of fluid in said volume reservoir inversely according to the degree of relative movement between the movable and stationary parts of the vehicle to thereby vary the pressure of fluid in the brake cylinder directly according to the increase in load.

8. In a variable load brake apparatus for a vehicle truck having a relatively stationary part and also having a part movable vertically relative to the stationary part as the load on the vehicle is increased, in combination, a brake cylinder, a volume reservoir, control means forsupplying uid under pressure to said brake cylinder and said volume reservoir, means adjustable in accordance with relative vertical movement be tween the movable and stationary parts of the vehicle, a fluid pressure operated mechanism carried by the movable .part and comprising a strut movable into engagement with the stationary part for adjusting said means, valve means con-- ditionable for operation to limit the supply of iiuid under pressure to said volume reservoir to different degrees between zero and a predetermined maximum pressure, and fluid pressure operated mechanism including adjustable means for conditioning said valve means for operation to limit the volume reservoir pressure inversely between zero and the maximum pressure according to the degree of relative vertical movemenfy between the movable and stationary parts of the vehicle to thereby vary the pressure of iiuid in the brake cylinder directly according to the increase in load.

9. In a variable load brake apparatus for a vehicle truck having a relatively stationary part and also having a part movable vertically relative to the stationary part as the load on the vehicle is increased, in combination, a brake cylinder, a volume reservoir, control means for sup plying uid under pressure to said brake cylinder and said volume reservoir, means adjustable in accordance with relative vertical movement between the movable and stationary parts of the vehicle, a fluid pressure operated mechanism carried by the movable part and comprising a strut movable into engagement with the stationary part for adjusting said means, valve means conditionable for operation to limit the pressure of fluid in the volume reservoir inversely between zero and a predetermined maximum pressure in accordance with the degree of relative vertical movement between the movable and stationary parts of the vehicle to thereby vary the pressure in the brake cylinder directly according to the increase in load, an adjustable member for conditioning said valve means, and uid pressure responsive means for positioning said adjustable means.

10. In a variable load brake apparatus for a vehicle truck having a relatively stationary part and also having a part movable vertically relative to the stationary part as the load on the vehicle is increased, in combination, a brake cylinder, a volume reservoir, control means for supplying uid under pressure to said brake cylinder and said volume reservoir, means adjustable in accordance with relative vertical movement between the movable and stationary parts of the vehicle, a uid pressure operated mechanism carried by the movable part and comprising a strut movable into engagement with the stationary part for adjusting said means, valve means conditionable for operation to vary the attainable limit of volume reservoir pressure inversely according to the degree of relative vertical movement between the movable and stationary parts of the vehicle to thereby vary the pressure in the brake cylinder directly according to the increase in load, uid pressure operated adjustable means for conditioning said valve means, and means including a movable abutment responsive to the pressure of fluid in a chamber and a spring operative ,upon a predetermined reduction in pressure in said chamber for supplying uid under pressure to said iluicl pressure operated adjustable means.

GLENN T. McCLURE. 

